( ) In sociolinguistics，speech community refers to a group of speakers who constitute a community and share the same language or a particular variety of language．Speakers of English in general might be treated as such a community.

制造厂承修自产设备，其修理质量容易保证，主要在于（）。

A、人员和设备的自身优势

B、管理和技术的自身优势

C、设备和技术的自身优势

D、技术和备件的自身优势