He . . . . . . . . to unlock the door to his flat because the telephone . . . . . . . ..

The correct answer is C. hurried/was ringing.

The sentence is in the past tense, so the verb “hurry” must also be in the past tense. The verb “ring” can be either in the past tense or the present perfect tense, depending on whether the speaker is focusing on the act of ringing or the fact that the phone has rung. In this case, the speaker is focusing on the act of ringing, so the verb “ring” should be in the past tense.

Here is a brief explanation of each option:

• A. was hurrying/rang: This option is incorrect because the verb “hurry” is in the present tense, while the rest of the sentence is in the past tense.
• B. hurries/has been ringing: This option is incorrect because the verb “hurries” is in the present tense, while the rest of the sentence is in the past tense. The verb “has been ringing” is also incorrect because it focuses on the fact that the phone has rung, rather than the act of ringing.
• C. hurried/was ringing: This option is correct because the verb “hurried” is in the past tense, and the verb “was ringing” focuses on the act of ringing.
• D. is hurrying/rings: This option is incorrect because the verb “is hurrying” is in the present tense, while the rest of the sentence is in the past tense. The verb “rings” is also incorrect because it focuses on the fact that the phone has rung, rather than the act of ringing.
• E. has hurried/has rung: This option is incorrect because the verb “has hurried” is in the present perfect tense, while the rest of the sentence is in the past tense. The verb “has rung” is also incorrect because it focuses on the fact that the phone has rung, rather than the act of ringing.