Explanation:
The correct answer is option 'B' - "is building". Let's break down the given sentence to understand why this is the correct answer.

The sentence talks about a future event, stating that "the city council ___________________ a new shopping centre in town next year." This means that the action of building the shopping center will happen in the future.

Here are the reasons why the other options are not correct:

- Option 'A' - "was going to build": This option uses the past tense "was going," which implies that the action was planned in the past but did not happen. However, the sentence clearly states that the shopping center will be built in the future, so this option is incorrect.

- Option 'C' - "would be building": This option uses the conditional verb form "would be building," which is used to talk about hypothetical or imagined situations. However, the sentence does not indicate any hypothetical situation but rather a definite plan for the city council to build the shopping center. Therefore, this option is incorrect.

- Option 'D' - "were building": This option uses the past tense "were building," which implies that the action was happening in the past. However, the sentence clearly states that the shopping center will be built in the future, so this option is incorrect.

Conclusion:
The correct answer is option 'B' - "is building" because it uses the present continuous tense to indicate a future action. The sentence states that the city council will build a new shopping center in town next year.

It's fixed that it will start from Next year... so, if it is written next year .. u either have to select the option in present or future... but in the option future related options are not given... so, option b is 100% correct