In this direct and indirect speech question, choose the best indirect version of the sentence "The teacher said to the students, \"Work hard now if you wish to have a better future.\"".

Introduction / Context:
This question tests the rules of converting an imperative sentence with a condition from direct speech into reported or indirect speech. The original sentence is a piece of advice from a teacher telling students to work hard in the present in order to enjoy a better future. When we report this speech, we need to change the reporting verb, adjust pronouns and time expressions, and maintain the conditional "if" clause correctly.

Given Data / Assumptions:

• Direct speech: "The teacher said to the students, \"Work hard now if you wish to have a better future.\""
• Reporting verb: "said to", which is usually changed to "advised" for suggestions and guidance.
• The command is "Work hard now", followed by the conditional clause "if you wish to have a better future".
• We are converting to reported speech in the past.

Concept / Approach:
For imperatives in indirect speech, we use an infinitive structure with "to" plus the base verb and often choose a reporting verb like "advised", "told", or "requested". Time expressions such as "now" usually change to "then" when the reporting verb is in the past. In the "if" clause, "wish" should normally be back shifted to "wished" to keep tense consistency in reported speech. Pronouns remain "they" because the subject is still the students. So, the ideal structure is "The teacher advised the students to work hard then if they wished to have a better future."

Step-by-Step Solution:
Step 1: Change "said to the students" to a suitable verb of advice: "advised the students". Step 2: Convert the imperative "Work hard" into an infinitive of purpose: "to work hard". Step 3: Change the time expression "now" to "then" because the reporting verb is in the past tense. Step 4: Back shift the verb in the conditional clause from "wish" to "wished". Step 5: Combine everything into the final reported sentence: "The teacher advised the students to work hard then if they wished to have a better future."

Verification / Alternative check:
Check each option against the rules. Option a) uses "advised", correctly changes "now" to "then", uses the infinitive "to work hard", and back shifts "wish" to "wished". Option b) keeps "now" instead of "then", which is acceptable only in special cases where the advice still applies at the moment of reporting, but exam questions usually expect the standard back shift. Option c) uses "then" but keeps "wish", mixing time references. Option d) keeps both "now" and "wish", which ignores back shift rules entirely. Therefore, option a) is the strongest and most rule consistent choice.

Why Other Options Are Wrong:
Option b) keeps "now", which clashes with the past reporting verb "advised" in typical exam style questions.

Option c) changes "now" correctly to "then" but leaves "wish" in present tense, resulting in a partial back shift.

Option d) keeps both present time reference "now" and present tense "wish", which is not expected in standard indirect speech when the reporting verb is past.

Common Pitfalls:
Students often forget to change "now" to "then" or do not apply back shift in the conditional clause. Another common mistake is to keep the imperative structure instead of using "to" plus the verb. A useful checklist for similar questions is: adjust the reporting verb, convert the command into an infinitive, update time expressions, and back shift verbs where appropriate.

Final Answer:
The correct reported version is: "The teacher advised the students to work hard then if they wished to have a better future."