Gaurav ranks eighteenth from the top in his class. What is his rank from the bottom of the class? Consider the following statements: I. There are 47 students in the class. II. Jatin, who is also in the same class, ranks tenth from the top and thirty eighth from the bottom.

Introduction / Context:
This data sufficiency question deals with rankings from the top and from the bottom in a class. We are told Gaurav rank from the top and asked to find his rank from the bottom. Two statements provide information about the total number of students, one directly and one indirectly through another student ranking. The aim is to decide which statements allow us to compute Gaurav rank from the bottom.

Given Data / Assumptions:

• Gaurav ranks eighteenth from the top in his class.
• Statement I: There are 47 students in the class.
• Statement II: Jatin ranks tenth from the top and thirty eighth from the bottom.
• Ranking is strictly by position with no ties, and the class size is fixed.

Concept / Approach:
The standard relationship between a position from the top, a position from the bottom, and the total number of students is: total = rank from top + rank from bottom minus 1. If we know any two of these three quantities for a student, we can find the third. Once the total number of students is known, Gaurav rank from the bottom follows directly from his rank from the top.

Step-by-Step Solution:
Step 1: Use statement I alone. If there are 47 students in the class and Gaurav is eighteenth from the top, then his rank from the bottom is 47 minus 18 plus 1. That is 29 plus 1 equals 30. So Gaurav is thirtieth from the bottom. Step 2: This shows that statement I alone is sufficient, because once the total number of students is given, the calculation is straightforward and unique. Step 3: Now use statement II alone. For Jatin, the relationship total = rank from top + rank from bottom minus 1 becomes total = 10 + 38 minus 1. That is total = 47. Thus statement II alone also yields the total number of students as 47, without directly stating it. Step 4: After deducing that there are 47 students from statement II, we can repeat the same calculation as in Step 1 for Gaurav, again finding that Gaurav is thirtieth from the bottom. Step 5: Because each individual statement allows us to determine the class size and therefore Gaurav rank from the bottom, each statement alone is sufficient. Therefore the correct classification is that either I alone or II alone is sufficient.

Verification / Alternative check:
As a cross check, consider whether any other class size could be consistent with statement II. If the class size were not 47, the sum of Jatin ranks from both ends minus 1 would not equal the total. Since the equality holds, the total must be exactly 47. Consequently, the logic of the calculation for Gaurav is forced. There is no alternative interpretation that changes his position from the bottom, so sufficiency is confirmed.

Why Other Options Are Wrong:
Option A claims only statement I is sufficient and implicitly suggests that statement II alone is not sufficient, which contradicts the fact that II allows us to compute the class size. Option B incorrectly gives sufficiency only to statement II. Option D claims that both statements together are necessary, which is not correct because we do not need to combine them. Option E, which says that even both are not sufficient, is clearly false because we have already obtained Gaurav rank from the bottom with each individual statement.

Common Pitfalls:
Learners sometimes forget the minus one in the relationship between top rank, bottom rank, and total students, leading to incorrect totals. Others may treat the information about Jatin as irrelevant because it does not mention Gaurav by name, overlooking that class size is the essential bridge. Remembering the standard formula and focusing on what is needed to link to the target student prevents these mistakes.

Final Answer:
The data either in statement I alone or in statement II alone are sufficient to answer the question, so the correct option is C.