Subject of the sentence ?

Hi~ In the final sentence below, what is the subject of the sentence?

Grammatically, it seems that the subject should be “The combination~ and the targeted OFIP” because of the verb “have”. But to me, it seems somewhat awkward by meaning. “The combination” looks more natural as the subject of the sentence for me. For your understanding, I put some more sentences.

Thank you very much for your help~!

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The third example is the school turnaround strategy in Ontario, called the Ontario Focused Intervention Partnership (OFIP). Consistent with the themes of this chapter, Ontario took a whole-system approach.

(omitted)

We won’t talk about the overall strategy, which is focused on raising the bar and closing the gap in literacy, numeracy, and high school graduation. I take only the OFIP component

(omitted)

Overall, more than 800 (of the 4,000) elementary schools have been engaged in OFIP, signaling that this is a systemwide effort. As of 2014, there are now 69 schools remaining in the OFIP group. The combination of the across-theboard strategy of raising the bar and closing the gap and the targeted OFIP have significantly reduced the gap for key subgroups: