Option 1 -> Present perfect continuous tense (has been + verb-ing), correctly used with "since morning" to show an action that started in the past and continues to the present.
Option 2 -> Grammatically incorrect; "has" cannot be directly followed by the -ing form without "been."
Option 3 -> Grammatically incorrect; "will" must be followed by the base form of the verb, not the -ing form.
Option 4 -> Simple present form doesn't work with "since morning," which requires a perfect tense to indicate duration from past to present.
Hence, Option 1: has been raining -> "Since morning" indicates an action that began in the past and continues into the present, requiring the present perfect continuous tense structure -> correct