Question

A forma negativa da frase: “She cooked last week.” é:
She wasn´t cooked last week.
She didn´t cook last week.

She didn´t cooked last week.
She weren´t cooked last week.

Answer 1

doesn't=present tense
didn't=past tense

She doesn't want to go today
She didn't want to go yesterday

O Didn’t se usa no passado
Doesn’t se usa no presente

No caso da sua questão ambas estão no passado . Por isso o uso do Didn’t .

Answer 2

Resposta:

B) She didn't cook last week