DCA

The Linux open source operating system, or Linux OS, is a freely distributable, cross-platform operating system based on Unix that can be installed on PCs, laptops, netbooks, mobile and tablet devices, video game consoles, servers, supercomputers and more.
Basic Features:
1) Portable - Portability means software can works on different types of hardware in same way. Linux kernel and application programs support their installation on any kind of hardware platform.
2) Open Source - Linux source code is freely available and it is community based development project.

Hi,
You may contact Brainware, CMC or NIIT.

BCA undoubtedly is a better course, as DCA is only a diploma course and BCA is a full time UG course. Even the job opportunities and scope is far better for the BCA course.

I think you should go for Science because it has more options than commerce.

You can enroll in any nearby computer institute, which is affiliated by a government university. NIELIT also conducts online examination every month and gives a government recognized certificate for CCC course.

Kindly be more specific about the university in which you want to take admission.

Diploma in Computer Applications (DCA) courses are usually six months, but could be a year depending on the course curriculum and institution. The objective of DCA course is to develop professionals to meet the requirement of office automation and electronic data processing. Students are introduced to different computer application software with their practical usage.

Please see below link:
https://www.shiksha.com/diploma-in-computer-applications-dca-article-4575-1