In the Academy Awards held in 2016 for films released in 2015, which of the following actresses won the Oscar for Best Actress in a Leading Role?

Introduction / Context:
The Academy Awards, commonly known as the Oscars, are the most widely followed film awards in the world. For general knowledge exams, questions often focus on major categories such as Best Film, Best Director, Best Actor, and Best Actress. In the 2016 Oscars, which honoured films from 2015, the Best Actress category gained attention because of several strong performances. This question asks you to identify which actress actually won the Oscar for Best Actress in a Leading Role that year.

Given Data / Assumptions:
- The year of the ceremony is 2016, covering films released mainly in 2015.
- The category is Best Actress in a Leading Role.
- Options include Brie Larson, Cate Blanchett, Jennifer Lawrence, Charlotte Rampling, and Saoirse Ronan.
- We assume familiarity with the film Room and its critical acclaim.

Concept / Approach:
The essential concept is matching the correct performer and film to the award year. Brie Larson won the 2016 Oscar for Best Actress for her powerful performance in the film Room, where she played a young woman held captive with her son. Cate Blanchett, Jennifer Lawrence, Charlotte Rampling, and Saoirse Ronan were also associated with major roles and nominations during that season but did not win the award. Remembering the pairing of Brie Larson and Room is the simplest way to arrive at the correct answer.

Step-by-Step Solution:
Step 1: Note that the question concerns the 2016 Oscars and the Best Actress category.
Step 2: Recall the widely reported news that Brie Larson won the Best Actress award for her performance in Room.
Step 3: Recognise that Cate Blanchett and Jennifer Lawrence are previous winners and frequent nominees, which can be confusing.
Step 4: Remember that Charlotte Rampling and Saoirse Ronan were also nominated but did not win in 2016.
Step 5: Select Brie Larson as the only actress in the list who actually took home the Best Actress Oscar that year.

Verification / Alternative check:
Exam oriented current affairs notes often highlight key Oscar winners with simple pairings such as Best Actress 2016, Brie Larson for Room. If you construct a small table in your mind linking year, category, and winner, you can quickly verify that Brie Larson aligns with 2016 and the Best Actress award. No such pairing exists for the other options in that exact year and category.

Why Other Options Are Wrong:
Cate Blanchett is a multiple Oscar winner and nominee but did not win the Best Actress award at the 2016 ceremony.

Jennifer Lawrence won an earlier Best Actress Oscar for Silver Linings Playbook but did not win in 2016.

Charlotte Rampling was nominated for her role in 45 Years but did not receive the award.

Saoirse Ronan was also nominated for Brooklyn in the same season; however, the award went to Brie Larson, making this option incorrect.

Common Pitfalls:
Candidates may confuse nomination with winning and choose any famous actress associated with that awards season. Another pitfall is mixing up years, such as recalling Jennifer Lawrence win from an earlier ceremony and mistakenly mapping it to 2016. A good strategy is to tie each year to one or two landmark winners you remember clearly, which reduces such confusion in the exam hall.

Final Answer:
The 2016 Oscar for Best Actress in a Leading Role was won by Brie Larson.