Part C violates the first conditional rule Key Points 'this summer we will go' should be there in place of 'this summer we would go' Conditional Type 1: It is possible and also very likely that the condition will be fulfilled. Form: if + Simple Present, will-Future Example: If I find her address, I’ll send her an invitation. Additional Information Second Conditional: It is possible but very unlikely, that the condition will be fulfilled. Form: if + Simple Past, Conditional (= would + Infinitive) Example: If I found her address, I would send her an invitation Third conditional sentences are used to explain that present circumstances would be different if something different had happened in the past. Rule: If + had + past participle + (would + have + past participle) in the main clause. Example: If you had worked harder, you would have passed your exam. ​Thus, the correct sentence is: My mother said to me "if we are going on a holiday this summer we will go to Egypt"